Cracked barrel detection system

ABSTRACT

A crack test includes flowing pressurized fluid to a generally tubular part in a flare stamping process. As the flare is completed the part is sealed on opposite ends and pressurization of the inside of the part is used to determine integrity of the part.

FIELD OF THE INVENTION

The present invention relates generally to stamped parts and components and, more particularly, the invention pertains to test systems and procedures for identifying cylindrical parts with cracks therein.

BACKGROUND OF THE INVENTION

Stampings and progressive stampings are used to manufacture parts and pieces of many different types and shapes for use in a variety of different assemblies and constructions. Metal can be shaped into many different forms and configurations by the application of force causing a metal blank to conform to the shape of a die used while applying the force. Simple parts and pieces can be made by a single stamping. In a single stamping, force is applied in a single event so that the metal conforms to a die used while applying the force. For more complex parts or parts taking a shape quite different from the original metal blank, progressive stampings are used. In progressive stampings, a series of dies are used in a series of stamping events, with each die and each stamping event forming the metal in stages from the original blank to the desired final formation.

It is known to use stamping techniques to form ends on parts having cylindrical bodies, including the formation of an expanded area or flare at an end of the cylindrical body. For example, a substantially cylindrical or tubular part can be stamped to have an outwardly bulged or flared portion at one end thereof. The initial flaring process can be a precursor, or preliminary step to a subsequent operation. By way of example, it is known to flare a tube end and then compress the flared portion in a folding manner onto itself to produce a two layer thick foot or flange at the end of tube. Parts as described can be used as a compression limiters or load-bearing parts for other purposes.

Elongated tubular parts can be susceptible to cracking during stamping processes. Force applied against hollow, elongated parts such as tubes or the like when forming flanges or flares is substantially axial, and can cause cracks to form along relatively unsupported lengths during the stamping process. It is often difficult to identify such crack defects. Cameras and visual inspections are often inadequate. Even a hairline crack can be significant in detrimentally affecting the final strength of the part. Compression limiters and the like can fail if a small crack in the barrel thereof is allowed to propagate, thereby weakening the axial strength of the finished part.

Stamping is often selected as the process for making parts and pieces because a stamping event is a rapid occurrence, and the manufacturing process is quick and inexpensive, with minimal waste. To ensure a high percentage of quality parts are shipped to customers cost effectively, testing procedures for stamped parts should be performed both rapidly and reliably. Preferably, a testing method occurs quickly so that testing or inspection of the part does not slow the overall process of making the part.

What is needed in the art is a crack testing apparatus that quickly and accurately identifies cracked parts such as a crack along the extended barrel of an elongated part that is hollow in the form of a tube, pipe or the like.

SUMMARY OF THE INVENTION

The present invention provides a testing device incorporated directly with a stamping press for identifying cracked parts or components during other steps in a stamping process.

In one aspect thereof, the present invention provides a process to identify cracks in a hollow part during a stamping procedure The process includes steps of loading a pre-form of the part into a press; pressing the pre-form of the part to form the part; sealing openings in the part; pressurizing the part in the press; and evaluating the pressure retained in the part.

In another aspect thereof, the present invention provides a stamping press with a flare pin and a die configured for receiving a first tube end and modifying a shape of the first tube end. A punch chuck assembly is configured for engaging an opposite tube end and urging the tube first end over the pin and into the die. A fluid pressure system includes a source of pressurized fluid and a fluid path through the punch chuck assembly and into a tube held by and between the pin and the die on one end and the chuck assembly on an opposite end.

In a still further aspect thereof, the present invention provides a stamping process for forming a flared end on a tube and for checking for cracks in the tube. The process has steps of providing a punch chuck assembly having a probe; providing a die block assembly with a flare pin and a die; positioning one end of a generally tubular part over the flare pin and into the die; positioning an opposite end of the generally tubular part over the probe; urging the part into the die block assembly to conform a profile of the tube to the flare die and pin and thereby forming a flared end; pressurizing the inside of the tube while retaining the tube between the die block assembly and the punch chuck assembly; and rejecting the part if a pressure inside the part is below a pre-established minimum pressure.

An advantage of the present invention is providing a device that can identify cracked components so that the cracked component can be discarded.

Another advantage of the present invention is providing a device for identifying cracked components in which crack defects appear along the extended lengths of hollow components such as tubes, pipes or the like.

Still another advantage of the present invention is providing a cracked component identifying system incorporated directly with a press performing a stamping process, so that a flawed part can be identified immediately and quickly.

Still another advantage of the present invention is providing a crack detecting system for tubes that operates in conjunction with a press, such as a flaring press, for performing other functions so that no additional time is required for testing the tubular body and the manufacturing process is not adversely impacted.

Other features and advantages of the invention will become apparent to those skilled in the art upon review of the following detailed description, claims and drawings in which like numerals are used to designate like features.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view of a press having a crack detection system in accordance with the present invention, the press being illustrated in readiness to perform a stamping operation and conduct a crack test;

FIG. 2 is a cross-sectional view of the press and part shown in FIG. 2, illustrating testing of an acceptable part;

FIG. 3 is a cross-sectional view similar to that of FIG. 2, but illustrating testing on a defective part; and

FIG. 4 is an exploded, cross-sectional view of a portion of the press shown in the preceding drawings.

Before the embodiments of the invention are explained in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangements of the components set forth in the following description or illustrated in the drawings. The invention is capable of other embodiments and of being practiced or being carried out in various ways. Also, it is understood that the phraseology and terminology used herein are for the purpose of description and should not be regarded as limiting. The use herein of “including”, “comprising” and variations thereof is meant to encompass the items listed thereafter and equivalents thereof, as well as additional items and equivalents thereof.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring now more specifically to the drawings and to FIG. 1 in particular, a punch press assembly 10 is shown. Punch press assembly 10 includes a crack test system 12 in accordance with the present invention which works in conjunction with a die block assembly 14 and a punch chuck assembly 16 and of press assembly 10. Punch press assembly 10 in the exemplary embodiment is shown as a flaring press for forming a flare on the end of a pre-formed part 18 to complete a finished part 20 having a flare 22 on the end thereof (FIG. 2). It should be understood that the configuration of pre-formed part 18 and finished part 20 are exemplary in nature and should not be considered as limiting of the present invention. The concepts of the present invention can be used to form other types of parts, different from those shown in the example.

While FIG. 1 is shown and described to have pre-form part 18, and FIG. 20 is shown and described to have completed part 20, it should be understood that in referencing a part as being a “completed part” it is intended to mean only with respect to the stamping step shown. It is not intended to mean that no further formation or alterations are made to further configure the part. While the present invention can be used and the test performed on a fully completed part, the present invention also can be used at an intermediate stage of a progressive stamping so that defective parts can be immediately identified and removed from further process steps. Alternatively, defective parts identified utilizing the present invention can be flagged for later removal at a more convenient time and stage of the process overall.

Die block assembly 14 includes a die block 30 configured for holding and securing a flare die 32 and a flare pin 34 therein. Flare pin 34 includes a contoured distal end 36 for receiving pre-form part 18 thereon. Specifically, a first end 38 of pre-form part 18 is engaged over distal end 36 of flare pin 34 in flare die 32. Relative axial movement between pre-form part 18 and die block assembly 14 causes first end portion 38 of pre-form part 18 to conform to the configurations of flare die 32 and distal end 36. Accordingly, the relative axial movement causes first end 38 to be shaped into flare 22 illustrated in FIG. 2.

Punch chuck assembly 16 is provided for engaging pre-form part 18 and exerting force, causing the relative axial movement between pre-form part 18 and die block assembly 14, with die block assembly 14 generally being kept in fixed position. Thus, punch chuck assembly 16 is adapted and arranged to engage an opposite end 40 of pre-form part 18 that is opposite to first end portion 38, and to force pre-form part 18 into die block assembly 14.

Punch chuck assembly 16 includes a punch or probe 50 adapted to slide into pre-form part 18 through end opposite 40. A longitudinal opening 52 is provided through probe 50. A backup 54 is provided and includes a longitudinal opening 56 therein similar to opening 52. Backup 54 and probe 50 are held in a quill 58 such that longitudinal openings 52 and 56 are in substantial axial alignment allowing fluid flow therethrough.

Quill 58 is retained in a thimble 60 held on a punch chuck 62. Those skilled in the art will understand readily that punch chuck 62 is adapted for axial movement toward and away from die block assembly 14 for routine operation of press assembly 10.

Crack test system 12 includes a pressurized fluid source 70 from which pressurized fluid is supplied. Pressurized air is a suitable fluid for many operations and uses of the present invention; however, other fluids can be used as desired. Pressurized fluid source 70 is connected to punch chuck assembly 16 by a fluid conduit 72 through which pressurized fluid is supplied to backup 14 and specifically longitudinal opening 56 thereof. Thus, a supply of pressurized fluid is provided to longitudinal opening 56 and longitudinal opening 52 in punch probe 50.

A fluid pressure gauge 74 is provided for evaluating the pressure of fluid in conduit 72 and is connected to a controller 76 via a signal line 78. Controller 76 is configured to provide a suitable notification or response, depending on the pressure determined.

In the use of the present invention, pre-form part 18 is positioned on probe 50 and is urged over distal end 36 and into flare die 32. While this known flaring sequence and operation is being performed, in accordance with the present invention pressurized air flows from source 70 through conduit 72 and longitudinal openings 56 and 54. Air thereby enters pre-form part 18, and, during initial stages of the flaring operation, the air flows freely through and out of pre-form part 18. However, as the flaring operation nears completion, with pre-form part 18 being pressed into flare die 32 and over flare pin 34, a seal is formed retarding the outflow of pressurized air at first end 38. Similarly, a seal is formed at a confronting interface 80 between opposite end 40 and quill 58. Accordingly, the flow of air out of finished part 20 is retarded and pressure builds therein. As the pressure builds throughout finished part 20 and crack test system 12, pressure gauge 74 determines the level to which pressure builds. Controller 76 can be preprogrammed with a threshold pressure indicating proper formation of finished part 20, without cracks or defects allowing the escape of pressurized fluid. When the threshold pressure is reached, finished part 20 is considered to be an acceptable part and is transferred for further processing along the production line.

FIG. 3 illustrates a finished part 90 having a crack 92 therein. Crack 92 or malformations of a flare end 94 or opposite end 96 allow continued outflow of air from part 90. Accordingly, pressure gauge 74 and controller 76 will not determine that the threshold pressure has been reached, and as a result, part 90 will be considered a defective part. In an automated system, punch press assembly 10 can be configured with automatic reject chutes for transfer of the part to scrap processing. Alternatively, an appropriate alarm can be generated, such as a light or other visual signal, or an alarm or other audible signal to alert an operator that a defective part has been identified. Punch press assembly 10 can be disabled so that the operator can remove and dispose of the defective part.

As yet another alternative, in a computerized control system, the defective part can be flagged and allowed to continue along the processing stream. At some later point in the process the defective part can be removed.

While the invention has been described to provide substantially continuous flow of pressurized fluid through pre-form part 18 as finished part 20 is being generated, it should be understood that the flow of pressurized fluid need not be continuous. An intermittent flow of fluid can be used, with fluid flow commencing as the stamping process forming flare 22 is being completed.

Crack test system 12 works in conjunction with and essentially simultaneously as press 10 operates to form flared end 22 on finished part 20. Consequently, no additional time is required to perform the crack test in that the test occurs simultaneously with formation of flared end 22. No additional steps are required in the manufacturing process for performing testing, with the testing instead being performed at a station already present for forming the flared end. The test is simple, automatic and effective.

Variations and modifications of the foregoing are within the scope of the present invention. It is understood that the invention disclosed and defined herein extends to all alternative combinations of two or more of the individual features mentioned or evident from the text and/or drawings. All of these different combinations constitute various alternative aspects of the present invention. The embodiments described herein explain the best modes known for practicing the invention and will enable others skilled in the art to utilize the invention. The claims are to be construed to include alternative embodiments to the extent permitted by the prior art.

Various features of the invention are set forth in the following claims. 

1. A process to identify cracks in a hollow part during a stamping procedure, said process comprising steps of: loading a pre-form of the part into a press; pressing the pre-form of the part to form the part; sealing openings in the part; pressurizing the part in the press; and evaluating the pressure retained in the part.
 2. The process of claim 1, including performing said sealing step in conjunction with said pressing step.
 3. The process of claim 2, including supplying pressurized air for said pressurizing step.
 4. The process of claim 1, including supplying pressurized air for said pressurizing step.
 5. The process of claim 1, said step of pressing including forming a flared end on the pre-form part.
 6. The process of claim 5, including sealing ends of the pre-form between a flare pin and die on one end and a quill and a punch on an opposite end while pressing the pre-form part.
 7. The process of claim 1, including sealing ends of the pre-form between a flare pin and a die on one end and a quill and a punch on an opposite end while pressing the pre-form part.
 8. The process of claim 1, including supplying a substantially continuous flow of pressurizing fluid through the perform part during said steps of pressing, sealing and pressurizing.
 9. A stamping press comprising: a flare pin and a die configured for receiving a first tube end and modifying a shape of the first tube end; a punch chuck assembly configured for engaging an opposite tube end and urging the tube first end over said pin and into said die; and a fluid pressure system including a source of pressurized fluid and a fluid path through said punch chuck assembly and into a tube held by and between said pin and said die on one end and said chuck assembly on an opposite end.
 10. The stamping press of claim 9, said punch chuck assembly including a probe configured to enter a tube processed on said press, said probe including a longitudinal opening therethrough, said opening being in flow communication with said fluid pressure system.
 11. The stamping press of claim 10, said fluid pressure system having a source of pressurized air.
 12. The stamping press of claim 10, said probe being held in a quill, and said quill configured to form a seal with a tube held between said flare pin and said die on one end and said quill on an opposite end.
 13. The stamping press of claim 12, said fluid pressure system having a source of pressurized air.
 14. The stamping press of claim 9, said fluid pressure system having a substantially continuous source of pressurized fluid.
 15. A stamping process for forming a flared end on a tube and for checking for cracks in the tube, said process comprising steps of: providing a punch chuck assembly having a probe; providing a die block assembly with a flare pin and a die; positioning one end of a generally tubular part over the flare pin and into the die; positioning an opposite end of the generally tubular part over the probe; urging the part into the die block assembly to conform a profile of the tube to the flare die and pin and thereby forming a flared end; pressurizing the inside of the tube while retaining the tube between the die block assembly and the punch chuck assembly; and rejecting the part if a pressure inside the part is below a pre-established minimum pressure.
 16. The stamping process of claim 15, including forming a seal between the tube and the die and flare pin.
 17. The stamping process of claim 15, including forming a seal of the generally tubular part against the punch chuck assembly.
 18. The stamping process of claim 17, including forming a seal between the tube and the die and flare pin.
 19. The stamping process of claim 18, including performing said step of pressurizing after completing said step of urging.
 20. The stamping process of claim 15, including flowing pressurized fluid through the part while performing said step of urging the part into the die block assembly to conform a profile of the tube to the die and flare pin. 